Photosensitive composition containing a halogenated hydrocarbon photoactivator and a spirothionapthopyran,a spirocycloheptatriene,or a spirothiobenzopyran

ABSTRACT

A COMPOSITION OF MATTER COMPRISING SPIRO COMPOUNDS HELD IN A MATRIX SUBSTANCE AND EXHIBITING STABLE COLOR CHANGES UPON EXPOSURE TO RADIATION OF CHARACTERISTIC WAVELENGTH. THE COMPOSITION OF MATTER IS EXPOSED RO DATAMODULATED LIGHT OF SUCH WAVELENGTH TO PROVIDE PERMANENT RECORDS OF THE DATA.

United States Patent Ofice US. Cl. 96-48 R 13 Claims ABSTRACT OF THE DISCLOSURE A composition of matter comprising spiro compounds held in a matrix substance and exhibiting stable color changes upon exposure to radiation of characteristic wavelength. The composition of matter is exposed to datamodulated light of such wavelength to provide permanent records of the data.

CROSS REFERENCE TO RELATED APPLICATION The present application is a continuation-in-part of my co-pending application Ser. No. 881,340, filed Dec. 1, 1969, now abandoned.

BACKGROUND OF THE INVENTION The invention relates to a composition of matter and a method for the recording of high frequency signals by irradiating compounds with light modulated by such isignals to produce irreversible color changes as a function of the signals. The compounds may be generally classified as spiro compounds having at least one part of the molecule as a pyran or thiopyran system.

The possibility of using color changes in spiro compounds for the recording of data has already been suggested. Thus, US. Pat. No. 2,953,454 issued Sept. 20, 1960, to E. Berman for Phototropic Data Storage Capsules and Base Coated Therewith discloses a radiationsensitive layer containing spirobenzopyran compounds for use in data recording. The spirobenzopyran compounds are held in the layer in dissolved form within a transparent, film-forming substance. Such a layer is suitable for a non-permanent storing of data, but it has the dis- 3,733,197 Patented May 15, 1973 Toward the goal of rendering the color changes in spiro-pyrans irreversible, the present inventor has shown in Federal Republic of Germany Auslegeschrift (published application) No. 1,274,655, issued Aug. 8, 1968, for a Speichermaterial zur Aufzeichnung hochfrequenter Signale (Storage Material for Recording High Frequency Signals), that such color changes can be made irreversible in both symmetric and asymmetric spirobipyrans as well as in compounds of the type spiro (pyrantrimethylindoline) by associating these compounds in a layer with a substance that splits into radicals when irradiated by the data-modulated light. The permanence of the color changes according to this method does not, however, prove sufiicient in all cases.

SUMMARY OF THE INVENTION An object of the present invention, therefore, is to provide compositions of matter and methods for achieving irreversible color changes in spiropyrans for the recording and storage of data.

Another object of the present invention is to provide compositions of matter and methods for achieving more permanent color changes in spiro compounds for the recording and storage of data than has heretofore been possible according to the teachings of German Auslegeschrift 1,274,655.

These as well as other objects which will become apparent in the discussion that follows are achieved, according to the present invention, by providing spiro compounds whose cationic molecule-part, formed after radiation-induced ring opening and fixed by development of a salt structure, exhibits such a charge delocalization that, for practical purposes, more permanent color changes are achieved. Ring opening and color change occurs preferentially under irradiation by light of a wavelength A at which maximum absorbance occurs. Besides light irradiation, electrons of equal energy can, for example, be used. All these types of radiation producing color change are referred to herein as actinic radiation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Investigations with systematically substituted 2,2- spirobi-[2H-1-benzopyran1s have shown that the stability of the color forms is determined by the electron density conditions in the cationic part of the molecules. This is illustrated by the behavior shown in Table 1 for some representative compounds. The measurements were advantage of not being suited for storage where permamade in acid solution.

TABLE 1.DONOR ANTI) ACCEPTOR SUBSTITUTION OF THE CAIIONIC ART OF THE MOLECULE Log e values me: After in my Immediate one hour G-metliyl-1-benzopyryliumperchlorate:

Q-fl-n-amyl-(2-hydroxy 5-methylstyryl) 532 4. 34 4. 37 2-fl-n-amyl-(2 hydroxy-S-bromostyryl) 512 4. 07 4. 08 fi-bromo-l-benzopyryliumperchlorate:

2-5-n-amyl-(2-hydroxy-5-methblstyryl) 532 }Absorbanc e very qulckly 2-B-n-amyl-(2-hydroxy-fi-bromostyryl) 528 decreasing Synthesis, data and method of determination of the tabulated values of these styrylpyrylium salts were given by C. Schiele, A. Wilhelm and G. Paal in Liebigs Annalen der Chemie 722, 162 (1969). Although every one of the above pyryliumperchlorates could be isolated as crystalline matter, continuous scanning of the spectra showed, that only spirobipyrans of the above kind with electron donating substituents in the later cationic molecule part yielded stable color forms due to high-grade charge delocalization in acid solution.

These investigations show that the stability of the color form resulting from the ring opening of the spiro compounds depends decisively on the amount the charge is spread out in the cationic molecule part A. Such spreading of the charge leads in turn to a marked mesomeric stabilizing.

For spirobipyrans, this spreading of charge in the color form built up after radiation-induced ring opening and stabilization by development of a salt structure is achieved by inducing a higher electron density at the C-atom neighboring the oxygen atom of the molecule part A of the basic spiro compound. This higher electron density is either increased or else first effected by substitution.

The invention proceeds from the recognition that, on the one hand, such a high-degree spreading of charge can be achieved by substituting for the oxygen atom of the pyran unit a heteroatom of lower electronegativity, for example sulfur; that, on the other hand, the spreading of charge can be achieved by constructing the molecule of the spiro compound in such a manner that a resonancestabilized cationic molecule part A is produced in the formation of the color form. The invention is characterized by spiro-thiopyans or spirocycloheptatrienes that are substituted in one of the double bonds neighboring the spiro C-atom at the carbon atom nearest the spiro C-atom.

Compounds of the following classes are within the invention:

(a) Spiro [2H- 1-thiobenzopyran-2,2'- 2H 1- benzopyran1s (b) Spiro [2H- l-thiobenzopyran-2,3 (3 H naphtho [2,1-b]pyran]s (c) Spiro 2H-1-thiobenzopyran-2,2'- (2H) naphtho [1,2-b]pyran] s (d) Spiro [2H-1-benzopyran-2,3 (3 H thionaphtho [2, l-b] pyran] s (e) Spiro [3H-thionaphtho[2,1-b]pyran-3,3 (3 H) naphtho[2,1-b]pyran]s (f) Spiro [2H-naphtho 1,2-b pyran-2,3'- (3 H) thionaphtho [2, l-b] pyran] s (g) Spiro [2H- l-benzopyran-2,2'- (2H) thionaptho [1,2-b]pyran] s (h) Spiro ZH-thionaphtho 1,2-b pyran-2,3 3 H) naphtho [2,1-b]pyran] s (i) Spiro ZH-thionaphtho 1,2-b] pyran-2,2- (2H) naphtho[1,2-b]pyran]s (j) 2,2-spirobi 2H- l-thiobenzopyran] s k) 3 ,3 -spirobi [3H-thionaphtho [2, 1-b]pyran] s (l) 2,2-spirobi(2H-thionaphtho 1,2-b] pyran] s (m) Spiro [ZH-1-thiobenzopyran-2,3 3 H) thionaphtho [2,l-b]pyran] s (n) Spiro 2H- 1-thiobenzopyran-2,2- 2H thionaphtho [1,2- py a s (o) Spiro [ZH-thionaphtho 1,2-b pyran-2,3 3 H) thionaphtho [2, l-b] pyran] s (p) Spiro [2H-1-benzopyran-2,7'-cycloheptatriene] s (q) Spiro [3H-naphtho[2,1-b]pyran-3,7-cycloheptatriene] s (r) Spiro 2H-naphtho[ 1,2-b] pyran-2,7-cycloheptatriene] s (s) Spiro [2H- l-thiobenzopyran-2,7'-cycloheptatrienc] s (t) Spiro 3H-thionaphtho [2, l-b] pyran-3,7'-cyclohe ptatriene] s (u) Spiro ZH-thionaphtho 1,2-b] pyran-2,7-cycloheptatriene] s Light absorption maxima achieved with compounds of these classes can be shifted by the fusing of additional benzene rings.

An improvement of the stability of the color form according to the present invention can also be achieved by selected substitution of the spiro compounds at the double-bonded carbon atoms that neighbor the spiro C-atom is compounds of the above classes since it has utmost importance for a predetermined ring opening as a step prior to the formation of the colored form. The mechanism 4 leading to the stability of the color form is illustrated by the following structural relations, where the color forms obtained immediately after ring opening are shown to the right of the arrow:

The dashed lines in the structural formulas represent omitted structure which is set forth for example in the above group of compounds. The inner dashed lines in the color forms right of the arrows represent the spreading of the positive charge. Here, A represents the cationic part of the color form and B represents the anionic part. X and Y represent, for example, oxygen or sulfur, and R is a substituent.

As brought out in German patent application No. P 17 68 664.5, filed June 14, 1968, by the present inventor, in the case of asymmetric spirobipyrans, ring opening of the pyran systems with the goal of gaining a desired cationic molecule part A can be predetermined by positioning of various substituents R in one of the double bonds neighboring the spiro C-atom at the atom of the double bond nearest the spiro C-atom. The wavelength at which ring opening occurs is subject to even greater control as brought out in Appendix I. A general method for structurally defined synthesis of these spiro compounds was given by C. Schiele, A. Wilhelm, D. Hendriks, M. Stepec and G. Paal in Tetrahedron, 24, 5029 (1968), and C. Schiele, G. Paal, G. Arnold and M. Stepec in Tetrahedron, 24, 5037 (1968). Examples of these substituents R are: saturated or unsaturated, linear or branched, alkyl groups having from 1 to 12, preferably 3 to 8 carbon atoms; halogen-substituted alkyl groups; HOCH OH; and substituted or unsubstituted phenyl groups.

Synthesis of the corresponding CH -R substituted pyryliumor thiopyrylium salts as the later cationic molecule parts A of the spiro compounds is the first step in synthesis of the above spiro compounds (a)-(o). Synthesis of the corresponding -CH R substituted tropylium salts as the later cationic molecule parts A of the above spiro compounds (p)-(u) was given by C. Jutz and F. Voithenleitner in Chemische Berichte, 97, 1337, 1349 (1964). Subsequent condensation of the ylium salts with aromatic o-hydroxyor o-mercaptoaldehydes according to the general method and cyclization of the resulting arylvinyl-derivatives finally yield the before mentioned spiro compounds. Exemplar application of such methods to prepare the spiro compounds of the present invention are as follows:

Condensation of 5-methyl-2-mercapto-benzaldehyde and 2-octanone according to the general method yields 2-n-hexyl 6 methyl 1 thiobenzopyryliumperchlorate. Further condensation with S-bromo-salicylaldehyde yields 2 [fl n amyl-(2-hydroxy-5-bromostyryl)]-6-methyl-lthiobenzopyryliumperchlorate, on cyclization 6-methyl- 3' n amyl 6' bromo-spiro[2H-1-thiobenzopyran-2,2- (2H)-1-benzopyran]. Ring opening of the spiro compound yields the predetermined 2-[B-n-amyl-(2-hydroxy- 5-bromostyryl) ]-6-methyl-l-thiobenzopyryliumsalt.

Condensation of 2-mercaptobenzaldehyde and 2-heptanone according to the general method yields 2-n-amyl- 1-thiobenzopyryliumperchlorate. Further condensation with l-hydroxynaphthaldehyde (2) yields Z-[B-n-butyl- (1-hydroxy-2-naphthyl)vinyl] 1 thiobenzopyryliumperchlorate, on cyclization 3'-nbuty1-spiro[2H-1-thiobenzopyran-2,2'-(2'H)naphtho[1,2-b]pyran]. Ring opening of the spiro compound yields the predetermined Z-[B-n-butyl- (1 hydroxy-2-naphthyl) vinyl] -1-thiobenzopyryliumsalt.

Condensation of tropyliumperchlorate and n-hexylmagnesiumbromide yields 7-n-hexyltropilidine, this on reaction with tritylperchlorate n-hexyltropyliumperchlorate. Further condensation with Z-hydroxy-naphthaldehyde(l) yields [B-n-amyl-(2-hydroxy-l-naphthyl)vinyl] tropyliumperchlorate, on cyclization 2-n-amyl-spiro[3H- naphtho[2,1-b]pyran-3,7-cycloheptatriene]. Ring opening of the spiro compound yields the predetermined [ii-amyl- (2-hydroxy-1-naphthyl)vinyl]tropyliumsalt.

According to a further development of the invention, a halogen donor is added to one of the compounds of the above classes. Examples of such donors are tribromoethanol, l-chloroanthraquinone, 1,3-dichloroacetone, and carbon tetrabromide. Such compounds have been mixed with recording spiro compounds, but never with compounds of the classes given above. See the Auslegeschrift No. 1,274,655 cited above.

In another development of the invention the stability of the color form is improved by additional substitution at the aromatic system of the cationic part of the above classes of spiro compounds. The substituents involved here are known in the literature.

The following are examples of procedure according to the present invention:

EXAMPLE I Five grams of a solution containing 5-20 weight percent polyvinylidene chloride, 0.1 to 3, preferably 0.3, weight percent t-butylcatechol, remainder Z-butanone, are mixed, by stirring, into 3 grams of a solution containing 2-10 weight percent cellulose aceto butyrate, remainder CHCl and 2 grams of a solution containing 1-5 weight percent 6-methyl-3'-n-amyl-6'-bromo-spiro[2H 1 thiobenzopyran-2,2-(2H)-1'-benzopyran], 0.3 to 1.5, preferably 1, weight percent 1,3-dichloroacetone, remainder CHCl The resultant solution is filtered using a fritted glass crucible. The filtrate is spread on a polyester sheet. When the solvent has evaporated, there is left on the polyester sheet a clear, transparent film of colorable substance.

The compound t-butylcatechol is used as a thermal polymerization inhibitor. See the above-cited Auslegeschrift No. 1,274,655. The compounds polyvinylidene chloride and cellulose aceto butyrate are used as a matrix substance for the spiropyran and as photopolymerizable material as described in Auslegeschrift No. 1,274,655. The purpose of the matrix substance is to hold the molecules of the spiropyran in fixed positions relative to one another so that a selective exposure of the molecules to data-modulated light and storage of the data is possible.

The product of this invention, for instance the coated sheet or film of this example, may be used in the exact same manner illustrated in FIGS. 2 and 3 of the abovecited US. Pat. No. 2,953,454 where the light is modulated by a stencil. However, the product has such a quick response that it may be run past a light beam modulated for example by a television transmitter to successfully store a broadcast.

The light source preferred for exposure of the product of this example is an Ar+ ion gas laser whose harmonic by internal frequency doubling of the fundamental wave shows a wavelength of 257.25 m It is not possible to reverse the color change obtained even though the product is exposed successively with light having wavelengths from 350 to 750 mu.

Submitting the composition for 24 hours to 60 degrees Celsius and 96% relative moisture showed superior per- 'manence of the exposed product of the sample as compared with the products of German Auslegeschrift No. 1,274,655.

EXAMPLE 11 As an example within the above Example I, five grams of a solution containing 15 weight percent polyvinylidene chloride, 0.3 weight percent t-butylcatechol, remainder 2-butanone, are mixed into 3 grams of a solution containing 5 weight percent cellulose aceto butyrate, remainder CHCI and 2 grams of a solution containing 3 weight percent 6-methyl-3' n amyl-6'-bromo-spiro[2H-1-thiobenzopyran-2,2'-(2'H)-1'-benzopyran], 1 weight percent 1,3-dichloroacetone, remainder CHCl One then proceeds as in Example I.

APPENDIX I While ring opening at a particular wavelength of maximum absorption is determined primarily by the abovediscussed substituents R in one of the double bonds neighboring the spiro C-atom at the atom of the double bond nearest the spiro C-atom, ring opening can be still further controlled by appropriate substitution of electron donors or electron acceptors in the aromatic rings. This is illustrated by the following examples.

The compound 3-n-amyl-spiro[2H-1-benzopyran-2,3' (3'H)naphtho[2,l-b]pyran], whose R-substituent as above described is n-amyl, undergoes ring opening at A =536 millimicrons. By substituting for the hydrogen atom at the G'position the following radicals, the following shifted values of x are obtained:

Radical: A (m i) CH O 560 'CH;,-- 547 Br 531 NO 508 The compound 3-n-amyl-spiro[2H-1-benzopyran-2,2'- (2'H)naphtho[1,2-b]pyran] undergoes ring opening at 7t =538 millimicrons. By substituting for the hydrogen atom at the 6-position the following radicals, the following shifted values of l are obtained:

Radical: A (mu) CH O 568 CH 554 Br- 531 NO 502 The above radicals at the 6-position are placed in the compounds of the present invention through the use of appropriately substituted aromatic o-hydroxyor o-mercaptoaldehydes in the above-described condensation of the ylium salts.

It will be understood that the above description of the present invention is susceptible to various modifications, changes, and adaptations, and that the same are intended vto be comprehended within the meaning and range of equivalents of the appended claims.

I claim:

1. A composition of matter consisting essentially of a compound means Within the formula and where R is selected from the group consisting of H, CH O, CH Br, and NO X being selected from the group consisting of O and S, R being means for achieving a spreading of charge above the spreading provided by the oxygen-containing pyran, R being spiro connected at the position shown in the formula and being selected from the group consisting of the thiobenzopyrans, thionaphthopyrans, and cycloheptatrienes.

2. A composition of matter as claimed in claim 1, wherein R is a thiopyran.

3. A composition of matter as claimed in claim 1, wherein R is a cycloheptatriene.

4. A composition of matter as claimed in claim 1, said compound means being selected from the group consist ing of compounds in the following classes:

Spiro [2H-1-thiobenzopyran-2,2'- (2'H) -1-benzopyran] s Spiro 2H-1 -thiobenzopyran-2,3- (3 H)naphtho[2,1-b]

pyran] s Spiro [2H-1-thiobenzopyran-2,2'-(2'H)naphtho[ 1,2-b]

pyran] s Spiro [2H- 1-benzopyran-2,3 3 H)thionaphtho[2,1-b]

pyran] s Spiro [3H-thionaphtho [2, 1-b]pyran-3,3 3 'H) naphtho [2, 1 -b]pyran] s Spiro [ZH-naphtho 1,2-b] pyran-2,3- (3 'H)thionaphtho [2, l-b]pyran] s Spiro [2H-1-benzopyran-2,2'- (2'H) thionaphtho 1,2-b]

pyran] s Spiro ZH-thionaphthol 1,2-b pyran-2,3 3H naphtho- [2,1-b]pyran]s Spiro [2H-thionaphtho[ 1,2-b pyran-2,2'- 2'H naphtho [1,2-b] pyran] s 2,2-spirobi 2H- 1 -thiobenzopyran] s 3,3-spirobi [3H-thionaphtho [2,1-b]pyran] s 2,2'-Spirobi[2H-thionaphtho[1,2-b]pyran]s Spiro 2H- l-thiobenzopyran-2,3 (3 'H thionaphtho [2,1-b]pyran] s Spiro [2H-1-thiobenzopyran-2,2'- (2'H) thionaphtho [1,2-b] pyran] s Spiro ZH-thionaphtho 1 ,2-b pyran-2,3- 3 'H) thionaphtho[2, l-b] pyran] s Spiro [2H- l-benZopyran-2,7-cycloheptatriene] s Spiro[3H-naphtho[2,1-b]pyran-3,7'-cycloheptatriene] s Spiro[2H-naphtho l ,2-b]pyran-2,7'-cycloheptatriene] s Spiro 2H- 1 -thiobenzopyran-2,7-cycloheptatriene] s Spiro 3H-thionaphtho 2, l-b pyran-3,7'-cycloheptatriene] s Spiro [2H-thionaphthol[ 1,2-b] pyran-2,7'-cycloheptatriene] s S. A composition of matter as claimed in claim 4, said compound means being 6-methyl-3'-n-amyl 6' bromospiro [2H-1-thiobenzopyran-2,2-(2'H)- 1'-benzopyran].

6. A composition of matter as claimed in claim 5, prepared by the following process, wherein the gram quantities represent proportions: mixing 5 grams of a solution containing 5-20 weight-percent polyvinylidene chloride, 0.1 to 3 weight-percent t-butylcatechol, remainder 2-butanone, with 3 grams of a solution containing 2-10 weightpercent cellulose aceto butyrate, remainder CHCl and 2 grams of a solution containing 1-5 weight-percent 6- methyl 3'-n-amyl-6'-bromo-spiro[2H-1-thiobenzopyran- 2,2-(2H)-l-benz0pyran], 0.3 to 1.5 weight-percent 1,3- dichloroacetone, remainder CHCI filtering the resultant solution, spreading the filtrate on a polyester sheet, and allowing solvent to evaporate, whereby a clear, transparent film of colorable substance on a polyester base is achieved.

7. A composition of matter as claimed in claim 1, said compound being substituted at an aromatic system of that part which is cationic in the color form.

8. A composition of matter as claimed in claim 1, wherein R is selected from the group consisting of saturated and unsaturated, linear and branched, halogen substituted and halogen unsubstituted alkyl groups having from 3 to 8 carbon atoms, HOCH OH-, and phenyl groups, and R is selected from the group consisting of CH30, CH3, BI', and NO2'.

9. A method of recording data, comprising the steps of mixing with a solidifiable matrix substance a halogen donor means and a compound means within the formula for exhibiting a color change by ring opening when exposed to a predetermined actinic radiation, said compound means and the halogen donor means being in a sulficient concentration to give an irreversible color change when exposed to a predetermined actinic radiation, R being selected from the group consisting of saturated and unsaturated, linear and branched, halogen substituted and halogen unsubstituted alkyl groups having from 1 to 12 carbon atoms, HOCH OH-, and phenyl groups, R being a substituent means for controlling the wavelength at which ring opening occurs, Ar being an aromatic means for further controlling the wavelength of ring opening and being selected from the group consisting of and where R is selected from the group consisting of H, CH O, CH Br--, and NO;;-, X being selected from the group consisting of O and S, R being means for achieving a spreading of charge above the spreading provided by the oxygen-containing pyran, R being spiro connected at the position shown in the formula and being selected from the group consisting of the thiobenzopyrans, thionaphthopyrans, and cycloheptatrienes, solidifying the matrix substance, and exposing the resultant body to such predetermined actinic radiation which has been modulated by data for storing the data.

10. A method as claimed in claim 9, wherein R is a thiopyran.

11. A method as claimed in claim 9, wherein R is a cycloheptatriene.

12. A method as claimed in claim 9, said compound means being 6-methyl-3'-n-amyl 6' bromo-spiro[2H-1- thiobenzopyran-2,2'- 2'H 1'-benzopyran] 13. A method as claimed in claim 9, the steps of mixing and solidifying comprising the following process, wherein the gram quantities represent proportions: mixing 5 grams of a solution containing 520 weight-percent polyvinylidene chloride, 0.1 to 3 weight-percent t-butylcatechol, remainder Z-butanone, with 3 grams of a solution containing 2-10 weight-percent cellulose aceto butyrate, remainder CHCl and 2 grams of a solution containing 1-5 weight-percent 6 methyl-3'-n-amyl-6-bromo-spiro[2H-1- thiobenzopyran 2,2 (2H)-1'-benzopyran], 0.3 to 1.5 weight-percent 1,3-dichloroacetone, remainder CHCl filtering the resultant solution, spreading the filtrate on a polyester sheet, and allowing solvent to evaporate,

3,486,899 12/1969 Brown 96-90 PC 3,532,638 10/1970 Otis 96-90 PC OTHER REFERENCES Photochromism: Spectroscopy Pyran and Thiopyran Derivatives, by R. S. Becker et al. in J. Phys. Chem. 72 (3), 998-1001 (1968).

NORMAN G. TORCHIN, Primary Examiner W. H. LOUIE, JR., Assistant Examiner US. Cl. X.R. 9690 PC 

